Turbine blade with reinforced leading edge

Abstract

The invention relates to a turbine blade comprising a blade root portion (4) and a blade body portion (5) comprising a core (10) made of a ceramic matrix composite material covered with an environmental barrier (11), the blade being characterized in that the thickness (e) of the environmental barrier on the blade body portion is greater than or equal to 1.0 mm on the leading edge (3) of the blade.

Description

Technical Field

[0001] This disclosure relates to an aircraft turbine blade made of a ceramic matrix composite material and a method for manufacturing such a blade. Background Technology

[0002] Ceramic matrix composites (CMCs) can withstand temperatures from 600°C to 1400°C.

[0003] Because CMC materials have excellent high-temperature resistance, they require less cooling. Since this cooling is typically drawn from the compressor, which can affect turbine efficiency, CMC materials improve engine efficiency, thereby reducing fuel consumption.

[0004] Furthermore, their use helps optimize turbine performance, particularly by reducing the total mass of the turbine, which further contributes to reducing fuel consumption and thus significantly reducing pollution emissions.

[0005] These advantages explain the industrial interest in developing this ceramic matrix composite.

[0006] However, CMC faces other challenges in industrial applications of aero-turbine turbines, especially turbine blades.

[0007] Specifically, ceramic matrix composites have poorer impact resistance compared to the metal alloys they replace.

[0008] In addition, compared with metal alloys, CMC blades exhibit less resistance to the physicochemical environment of the turbine.

[0009] Finally, blades made of CMC material are difficult to machine.

[0010] However, it should be noted that each problem has its own independent solution.

[0011] For example, there have been suggestions to add metal foil to the leading edge of blades made of composite materials to protect them from possible impacts.

[0012] Similarly, there have been suggestions to coat CMC blades with an environmental barrier to chemically protect them from corrosion and / or high temperatures.

[0013] Finally, a manufacturing method for CMC blades known as "near-net shape" was proposed, meaning that after fabrication, the blade shape is as close as possible to the desired shape for its intended use. The machining requirements for these blades are then strictly reduced to a minimum, significantly accelerating the manufacturing process.

[0014] However, overcoming these three problems using specific methods for each of them remains complex and expensive. Summary of the Invention

[0015] This invention is specifically aimed at a blade made of ceramic matrix composite material, which will solve the above three problems in a unique way.

[0016] Therefore, according to its first aspect, it relates to a turbine blade including a blade root portion and a blade body portion, the blade body portion including a core made of ceramic matrix composite material covered with an environmental barrier, the blade being characterized in that the thickness of the environmental barrier on the blade body portion is greater than or equal to 1.0 mm at the leading edge of the blade.

[0017] Understandably, in applications, the "thickness" of a layer is often understood as the minimum elongation dimension. Generally, this dimension is obtained in a direction perpendicular to the surface of the composite core material.

[0018] In one aspect of the invention, the environmental barrier layer provides excellent protection for the underlying CMC, shielding it from oxidation and corrosion, similar to environmental barriers in the prior art.

[0019] Furthermore, the thickness of the environmental barrier provides excellent protection for the leading edge of the blade, shielding it from impacts by foreign objects. In fact, the inventors observed that for environmental barriers of 1.0 mm or thicker, only the barrier itself is damaged upon impact, and it dissipates all impact energy within the barrier layer. Therefore, the vulnerability of the environmental barrier serves to dissipate all impact energy, ensuring that the barrier layer protects the underlying substrate and that the ceramic matrix composite portion of the blade remains undamaged.

[0020] Furthermore, if the environmental barrier layer is damaged during an impact, it is relatively easy to remove, especially with such a thick layer. Applying a new environmental barrier to the surface of the turbine blade is also much cheaper than repairing or replacing the composite core of such a blade.

[0021] This allows for the manufacture of blades that are much cheaper than existing technologies, and they do not need to be replaced if they are subjected to impact.

[0022] The cause of this effect on a running turbine could be, for example, the turbine inhaling a bird.

[0023] In the blade of the present invention, a ceramic matrix composite material forms the core of the blade, that is, it ensures mechanical properties and excellent grip on environmental barriers, but does not play an aerodynamic role.

[0024] In the blades according to the invention, it is indeed the environmental barrier that ensures the aerodynamic performance of the blades.

[0025] This greatly simplifies blade production because the machining to obtain the desired aerodynamic profile is carried out in an environmental barrier, rather than in CMC material.

[0026] Specifically, this can save all the effort usually required to achieve a sufficiently smooth CMC material surface finish to meet the aerodynamic requirements of turbine blades, since the CMC material exists only as the core of the blade, while the aerodynamic requirements of turbine blades are met by environmental barriers that are easier to machine.

[0027] Machining environmental barriers are much simpler than machining ceramic matrix composites because they are much harder than CMC materials.

[0028] Therefore, the present invention allows for a simpler solution to protect the leading edge of composite blades from impact than the prior art solution that requires attaching metal foil to the composite blade.

[0029] In one embodiment, the turbine blade according to the invention includes a blade root portion and a blade body portion, the blade body portion including a core made of ceramic matrix composite material covered with an environmental barrier, the blade being characterized in that the thickness of the environmental barrier on the blade body portion is greater than or equal to 1.0 mm at the leading edge of the blade, the thickness of the environmental barrier continuously decreases between the leading edge and the trailing edge, and the thickness of the environmental barrier is less than or equal to 40 micrometers at the trailing edge.

[0030] The statement "continuously decreasing" should be understood mathematically. The function representing the change in the thickness of the environmental barrier with distance from the leading edge is continuous and decreasing.

[0031] In one embodiment, the thickness of the environmental barrier can decrease strictly and continuously between the leading and trailing edges.

[0032] One advantage of this type of blade is that its trailing edge is as thin as that of existing blades, which is highly advantageous for aerodynamic reasons because the thickness of the environmental barrier is very small.

[0033] Therefore, due to the very thick environmental barrier covering the leading edge, this blade combines excellent protection for the blade core, and because the environmental barrier at the trailing edge is very thin, it also has excellent aerodynamic characteristics.

[0034] In one embodiment, the thickness of the trailing edge environmental barrier may include between 20 micrometers and 40 micrometers.

[0035] In one embodiment, the thickness of the environmental barrier in the root portion of the leaf is less than or equal to 100 micrometers.

[0036] In fact, since the root part of the blade is not impacted and does not require special processing for aerodynamic reasons, the environmental barrier does not need to be thicker than the blades of existing technologies.

[0037] In one embodiment, the environmental barrier comprises silicon, such as rare earth silicates or mullite. For example, the environmental barrier may comprise yttrium disilicate (Y₂Si₂O₇), ytterbium disilicate (Yb₂Si₂O₇), mullite (3Al₂O₃·2SiO₂), or a mixture of two or more of these compounds.

[0038] In one embodiment, the blade further includes an adhesive layer disposed between the ceramic matrix composite core and the environmental barrier.

[0039] In one embodiment, the adhesive layer may comprise silicon and / or silicon dioxide (SiO2), or may even be made of silicon dioxide (SiO2).

[0040] This adhesive layer ensures excellent chemical continuity between the thermal barrier and the CMC material. Furthermore, it provides excellent compatibility regarding thermal expansion between the CMC material and the thermal barrier, thereby reducing the risk of environmental barrier delamination during operation.

[0041] In one embodiment, the blades are selected from stationary blades, such as high-pressure distributor blades or low-pressure distributor blades, or moving blades, such as low-pressure turbine blades or high-pressure turbine blades.

[0042] In one embodiment, the blades are movable blades. In fact, these are the blades that are most susceptible to breakage upon impact, and therefore, it is particularly desirable for these blades to possess the aforementioned advantages.

[0043] In one embodiment, the blade includes a lower connecting portion between the blade root portion and the blade body portion, wherein the thickness of the environmental barrier in the lower connecting portion is strictly increased.

[0044] This connection ensures good mechanical continuity between the ceramic matrix composite parts of the blade body and the blade root.

[0045] Specifically, this avoids sudden changes in the thickness of the composite material portion, thereby avoiding areas of stress accumulation and reducing the overall fragility of the blade.

[0046] Preferably, this connecting portion has an extension dimension of less than or equal to 10 mm in the longitudinal direction of the blade, for example, between 3.0 mm and 10 mm.

[0047] By limiting the longitudinal dimensions of the lower connection section, where the thickness of the environmental barrier is less than that of the blade body, the aforementioned advantages precisely obtained through the thickness of the environmental barrier are preserved, while areas of stress accumulation are avoided.

[0048] The longitudinal direction of a leaf is understood as the direction of its maximum extension, generally extending from the leaf root towards the leaf body.

[0049] In one embodiment where the blade is a stationary blade, the blade may further include a blade tip portion, the thickness of which is less than or equal to 100 micrometers.

[0050] In fact, for the same reasons as the root portion of a leaf, the thickness of an environmental barrier does not need to be greater than that of a traditional leaf.

[0051] In one embodiment where the blade is a stationary blade, the blade may include a blade head portion and an upper connecting portion between the blade head portion and the blade body portion, wherein the thickness of the environmental barrier in the upper connecting portion is strictly increased.

[0052] The upper connection allows for the same advantages at the blade tip as the lower connection described above.

[0053] Preferably, this upper connecting portion has an extension dimension of less than or equal to 10 mm in the vertical direction of the blade, for example, between 3.0 mm and 10 mm.

[0054] Limiting the longitudinal dimensions of the upper connection allows for the same advantages at the blade tip as the lower connection described above.

[0055] In one embodiment, the ceramic matrix composite material is a SiC / SiC material.

[0056] According to another aspect, the present invention relates to a method for manufacturing a blade as described above, the method comprising the step of depositing an environmental barrier layer on a ceramic matrix composite core, followed by the step of machining the environmental barrier layer.

[0057] In one embodiment, prior to the step of depositing the environmental barrier layer, the method includes a step of depositing an adhesive layer on a core made of a ceramic matrix composite.

[0058] In one embodiment, the bonding layer comprises silicon and / or silicon dioxide (SiO2), and the bonding layer deposition step can be performed by physical vapor deposition (PVD), chemical vapor deposition (CVD), vacuum plasma spraying (VPS), or atmospheric plasma spraying (APS).

[0059] In one embodiment, the environmental barrier can be deposited by thermal projection, such as by plasma projection.

[0060] It should be noted that these methods differ from liquid-phase deposition processes typically considered in the prior art for depositing environmental barriers.

[0061] In fact, these liquid phase methods are not suitable for depositing thicknesses consistent with the thickness of the blade.

[0062] This is why plasma projection deposition of environmental barriers is preferred, as it is compatible with the thickness involved.

[0063] While thermal spray deposition techniques are not as precise as existing technologies, they allow for the deposition of significantly thick environmental barriers and can be machined. Subsequent machining steps correct any inaccuracies in the deposition process, which is why these cheaper deposition techniques can be chosen and allow for the deposition of thicker environmental barrier layers.

[0064] In one embodiment, the machining step can be performed by single-layer or multi-layer grinding.

[0065] According to another aspect, the present invention relates to a turbine comprising blades as described above.

[0066] According to another aspect, the present invention relates to an aircraft comprising a turbine as described above. Attached Figure Description

[0067] [ Figure 1 ] Figure 1 This is a schematic diagram of a turbine.

[0068] [ Figure 2 ] Figure 2 This is a schematic diagram of a blade from existing technology.

[0069] [ Figure 3 ] Figure 3 A blade is schematically shown in one embodiment of the invention.

[0070] [ Figure 4 ] Figure 4 The connection portion in one embodiment of the present invention is shown schematically.

[0071] [ Figure 5 ] Figure 5 The stacking method for obtaining the blades according to the invention is illustrated schematically. Detailed Implementation

[0072] The invention will now be described with reference to the accompanying drawings, which are used to illustrate certain embodiments of the invention and should not be construed as limiting these embodiments.

[0073] Figure 1 A cross-sectional view of the turbofan engine 21, taken along a vertical plane passing through its main axis A, is shown. It includes a fan 22, a low-pressure compressor 23, a high-pressure compressor 24, a combustion chamber 25, a high-pressure turbine 26, and a low-pressure turbine 27 along the airflow circulation from upstream to downstream.

[0074] It is known that the low-pressure compressor 23, the high-pressure compressor 24, the high-pressure turbine 26, and the low-pressure turbine 27 include stationary blades and moving blades, one or more of which can be as described above.

[0075] Figure 2 A blade 1 made of ceramic matrix composite material according to the prior art is shown.

[0076] This leaf 1 includes a main leaf body 5 and a leaf root 4.

[0077] The blade includes a leading edge 3 and a trailing edge 7. As shown in the figure, the leading edge 3 is reinforced by a metal foil 8 arranged thereon.

[0078] The metal foil 8 provides mechanical protection for the leading edge of the blade. In the event of an object being ingested by the engine, it is the metal foil, not the main body of the blade 5, that will come into contact with the object.

[0079] Therefore, the blade 1 is protected by the foil 8. However, this type of blade has disadvantages, particularly related to the arrangement of the foil 8 on the blade 1.

[0080] Specifically, the difference in the coefficient of thermal expansion between blade 1 and foil 8 makes it difficult to keep foil 8 on blade 5.

[0081] The blade according to the invention provides an alternative method for protecting the leading edge, which also ensures that the CMC material is protected from the corrosive and oxidizing environment of the turbine.

[0082] Figure 2 This further clarifies the transverse direction T and longitudinal direction L of the blade.

[0083] also, Figure 2 Indicated by dashed line III Figure 3 The cross-section of the view is represented by the dashed line IV. Figure 4 The position of the view.

[0084] However, it should be noted that these instructions are for reference only, because Figure 3 and Figure 4 The blades according to the invention, and Figure 2 These are blades from the prior art that are outside the scope of this invention.

[0085] Figure 3 A specific cross-section of the blade according to the invention is shown.

[0086] As mentioned above, Figure 3 The blades consist of a ceramic matrix composite core 10 and an environmental barrier 11.

[0087] Figure 3 This further clarifies the significance of the thickness of environmental barriers.

[0088] Therefore, the thicknesses e1, e2, e3, and e4 are represented at several points that are more or less close to the leading edge 3, with e1 being the closest to the leading edge 3 and e4 being the furthest.

[0089] exist Figure 3 In the illustrated embodiment, the thickness of the environmental barrier 11 in the blade of the present invention decreases between the leading edge 3 and the trailing edge 4.

[0090] As described above, the thickness e1 of the environmental barrier 11 at the leading edge 3 is greater than or equal to 1.0 mm.

[0091] at last, Figure 3 The thickness variation is continuous. This ensures excellent aerodynamic performance throughout the blade assembly.

[0092] Furthermore, it is important to understand that thickness changes are assessed independently on the suction side and the pressure side. In fact, as... Figure 3 As shown, the thickness of the environmental barrier 11 on the suction side and the pressure side can be different.

[0093] However, the thickness of the environmental barrier 11 decreases between the leading edge 3 and the trailing edge 4 on both the suction side and the pressure side.

[0094] In an embodiment not shown, the thickness of the environmental barrier may be constant and greater than or equal to 1.0 mm over the entire blade body.

[0095] Figure 4 This further explains the meaning of the connecting part 6. This connecting part is located between the root region 4 of the leaf and the main body region 5 of the leaf.

[0096] like Figure 4 As shown, the connecting portion 6 includes an environmental barrier 11, the thickness e of which gradually increases in the connecting portion 6.

[0097] Figure 4 The longitudinal extension H of the connecting part 6 is further explained. R The meaning of .

[0098] In one embodiment, the extension H of the connecting portion 6 R Less than or equal to 10 mm, for example, including those between 3.0 mm and 10 mm.

[0099] The connection section ensures good compatibility between the CMC portion of the blade body 5 and the blade root portion 4, while allowing the required thickness to be achieved quickly.

[0100] Figure 5 Finally, a stack of ceramic matrix composite core 10, adhesive layer 110 and environmental barrier 11 is shown.

[0101] In one embodiment, an adhesive layer 110 may be placed between the substrate 10 and the environmental barrier 11.

[0102] This embodiment allows for better resistance to delamination in the stack, particularly by improving the continuity of the coefficient of thermal expansion.

[0103] In addition, the adhesive layer 110 can play a role in protecting the composite substrate 10 from corrosion.

[0104] In one embodiment, the blade does not include any layers other than the ceramic matrix composite core 10, the adhesive layer 110, and the environmental barrier 11.

[0105] In other words, the adhesive layer 110 is in direct contact with the ceramic matrix composite core 10, while the environmental barrier layer 11 is in direct contact with the adhesive layer 110.

Claims

1. A turbine blade comprising a blade root portion (4) and a blade body portion (5), the blade body portion comprising a core (10) made of a ceramic matrix composite covered with an environmental barrier (11), characterized in that, The thickness (e) of the environmental barrier on the blade body portion is greater than or equal to 1.0 millimeter on the leading edge (3) of the blade.

2. The turbine blade of claim 1, wherein, The thickness of the environmental barrier decreases continuously between the leading edge and the trailing edge, with an environmental barrier thickness for the trailing edge (8) that is less than or equal to 40 microns.

3. Turbomachine blade according to claim 1 or 2, characterized in that The thickness of the environmental barrier (11) in the blade root portion (4) is less than or equal to 100 microns.

4. The turbine blade of any one of claims 1 to 3, wherein, The environmental barrier (11) comprises yttrium disilicate Y2Si207, ytterbium disilicate Yb2Si207, mullite (3Al203.2Si02) or a mixture of two or more of these compounds.

5. The turbine blade of any one of claims 1 to 4, wherein, An adhesion layer (110) is provided between the ceramic matrix composite core (10) and the environmental barrier (11).

6. The turbine blade of claim 5, wherein, The adhesion layer (110) comprises silicon and / or silicon dioxide Si02.

7. The turbine blade of any one of claims 1 to 6, wherein, The turbine blade is chosen from a high-pressure distributor blade, a low-pressure distributor blade, a high-pressure turbine blade or a low-pressure turbine blade.

8. The turbine blade of any one of claims 1 to 7, wherein, A lower connecting portion (6) is also included between the blade root portion (4) and the blade body portion (5), the thickness (e) of the environmental barrier (11) in the lower connecting portion increasing strictly.

9. A method of manufacturing a blade according to any one of claims 1 to 8, comprising the step of depositing an environmental barrier layer (11) on a ceramic matrix composite core (10), followed by the step of machining the environmental barrier layer.

10. The manufacturing method according to claim 9, wherein The step of depositing the environmental barrier (11) is performed by plasma projection.

11. The production method according to claim 9 or 10, characterized by, Before the step of depositing an environmental barrier layer (11), a step of depositing an adhesion layer (110) on a core made of ceramic matrix composite (10) is included.

12. An aeronautical turbine comprising a blade according to any one of claims 1 to 8.

13. An aircraft comprising an aeronautical turbine according to claim 12.

Images